I am facing a strange issue with syslog-ng v3.5.2 (also faced same issue with v3.9) running on centos 6.10.
After a few hours of running syslog-ng the machine becomes unresponsive, we cannot pass the ssh login screen, it accepts username but there's no password prompt. I cannot run any commands (crontab etc).
The only way to get into the machine, is to always keep an extra ssh session and login into that to kill syslog-ng. After killing syslog-ng machine becomes responsive again.
This machine accepts on average a couple of thousants packets per second from 300-400 hosts.

Did you look at `top` at the time? Or if you have sysstat installed then you could look at the output from `sar` to see some system stats. Sounds to me most likely you have something with a memory leak and it's using up all RAM and swapping like crazy at which point the machine will slow to a crawl...

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Did you look at `top` at the time? Or if you have sysstat installed then you could look at the output from `sar` to see some system stats. Sounds to me most likely you have something with a memory leak and it's using up all RAM and swapping like crazy at which point the machine will slow to a crawl...

Thanks for replying, it seems that cpu and memory is quite low. running syslog-ng in verbose mode it shows this error at some point: